KEANEKARAGAMAN DAN POTENSI STREPTOMYCETES RIZOSFER TEKI (Cyperus rotundus L.) DAERAH TERCEMAR MERKURI SEBAGAI AGEN BIOREMEDIASI CEMARAN LOGAM

SAIDATUL MAZIYAH, Drs. Langkah Sembiring, M.Sc., Ph.D.

2011 | Tesis | S2 Biologi

Dalam upaya mengetahui keanekaragaman streptomycetes daerah tercemar merkuri, streptomycetes diisolasi dari sampel tanah rizosfer teki (Cyperus rotundus L.) di sekitar quarry dengan metode isolasi selektif menggunakan media Starch Casein Agar (SCA) dan Raffinose-Histidine Agar (RHA). Kemampuan streptomycetes resisten terhadap merkuri ditentukan melalui tahap; (1) screening streptomycetes dengan metode sumuran, (2) seleksi streptomycetes dengan metode paper disk, (3) uji kuantitatif resistensi berdasarkan persentase pertumbuhan relatif serta persentase akumulasi dan atau reduksi merkuri. Letak pengikatan merkuri oleh isolat terpilih ditentukan berdasarkan jumlah merkuri dalam dinding dan membran sel (cell debris) serta sitoplasma (cell-free extract). Semua pengukuran jumlah merkuri dilakukan dengan Atomic Absorption Spectophotometry (AAS). Isolat resisten merkuri terpilih dikarakterisasi dan diidentifikasi berdasarkan sifat pengecatan gram, warna miselium dan pigmen, morfologi rantai spora menggunakan metode tilted cover slip, dan ornamentasi permukaan rantai spora menggunakan Scanning Electron Microscopy (SEM). Hasil penelitian menunjukkan terdapat keanekaragaman streptomycetes yang berasosiassi dengan akar Cyperus rotundus L. di daerah tercemar merkuri. Densitas dan diversitas streptomycetes dipengaruhi oleh tingkat pencemaran merkuri. Hasil uji kemampuan streptomycetes resisten merkuri diperoleh strain AS1 sebagai isolat resisten merkuri terpilih. Strain AS1 mampu mengikat merkuri pada sitoplasma, membran dan dinding sel. Isolat terpilih ini menunjukkan tipe gram positif, miselium aereal abu kecoklatan, miselium vegetatif krem, pigmen coklat, morfologi rantai spora bertipe spiral, dan ornamentasi permukaan spora bertipe smooth. Strain AS1 diduga merupakan spesies baru anggota genus Streptomyces. Isolat terpilih ini berpotensi untuk digunakan dalam bioremediasi cemaran merkuri.

To study the diversity of streptomycetes in mercury contaminated area, streptomycetes were isolated from rizosphere soil samples of purple nut sedge (Cyperus rotundus L.) around the quarry. Starch Casein Agar (SCA) and Raffinose-Histidine Agar (RHA) were used to streptomycetes selective isolation. The ability of mercury resistant streptomycetes was determined by stages of testing; (1) screening of streptomycetes used troughs method, (2) selection of streptomycetes used paper disk method, (3) quantitative test of resistance based on the percentage of relative growth and percentage of mercury acumulation and or reduction. Determination of mercury binding location by selected isolate was based on the amount of mercury in the membranes and cell walls (cell debris) and cytoplasms (cell-free extract). The measurements of amount of mercury were done by Atomic Absorption Spectophotometry (AAS). Characterization and identification of selected isolate were based on gram staining, mycelium and pigment colour, spore chain morphology using tilted cover slip methode, and spore chain surface ornamentation using Scanning Electron Microscopy (SEM). The results of the study showed there was diversity of streptomycetes associated with root system of Cyperus rotundus L. in mercury contaminated area. Density and diversity of streptomycetes were influenced by level of mercury contamination. The results of the mercury resistance test of streptomycetes was obtained strain AS1 as mercury resistant selected isolate. Strain AS1 was able to binding mercury in cytoplasms, membranes and cell walls. This selected isolate was gram positive. It has brownish gray aereal mycelium colour, cream vegetative mycelium colour, brown pigment colour, spore chain morphology type spiral, and spore chain surface ornamentation type smooth. Strain AS1 was suggested as a new species of Streptomyces genus member. This selected isolate has potential to be used to bioremediation of mercury contamination.

Kata Kunci : streptomycetes, rizosfer, merkuri, resistensi, bioremediasi